Method of making a hollow propeller blade



Feb 31, 1941. J. H. NELSON METHOD OF MAKING A HOLLOW PROPELLER BLADEFiled March 7, 1938 2 Sheets-Sheet l Feb. 11, 1941. J. H. NELSON METHODOF MAKING A HOLLOW PROP-ELDER BLADE Filed March '7, 1938 2 Sheets-Sheet2' c 51 um 50 positions shown Patented Feb. 11, 1941 mz'rnon or MAKING AnonLow morerun nuns 1.1... a. ram, Holden, m. designer to Wyman-Gordon-Company,

corporation of Worcester, Mass; a usetts Application smell 1, issaseriaiNo. 194,330 J 1 @laim. (c1. es-ms) This invention relates to propellerblades for aircraft enginesand particularly to hollow blades made ofsteelor other metal or alloy of high tensile strength and adapted to beforged and welded or brazed. In the following specification and claim,the term steel" is to be understood to'be descriptive only and toinclude ferrous alloys and all other metals or alloys which meettherequirements above set forth.

provide a hollow steel propeller blade of novel construction, and toprovide an improved method of manufacturing such a blade. 7

. More specifically, 1 provide a hollow steel blade 1 comprising twoforged casing portions and a single longitudinal reenforcing rib orstiffening member. all three parts being permanently secured together bywelding or brazing operations.

My invention further relates to certain arrange- 20 merits andcombinations of parts and to certain ordered procedure which will behereinafter described and more particularly pointed out in the appendedclaim.

A preferred form of the invention is shown in 2!! the drawings, in whichFig. l is a plan view of my improved propeller blade? Fig. 2 is a planview, partially broken away, and showing forged blanks from which thetwo 30 casing portions of my improved blade are formed; Figs. 3 and 4are transverse sectional views, taken along the lines 3-! and 4-4 inFig. 2 respectively;

Fi'gs. Sand 6 are sectional views corresponding 35 to Figs. 3 and 4 butshowing the blanks forged or pressed to finished shape;

Fig. 7 is aperspective view of a portion of the longitudinal stiffeningrib; Figs. 8 and 9 are transverse sectional views of 40 the finishedpropellentaken along the lines 0-! and 9-9 in Fig. 1 respectively; and 1V Fig. 10 is an enlarged detail sectional view to be described. h hReferring to Figs. 1, 8 and 9, I have shown a propeller blade B ofhollow cross section and 4 comprising casing portions 2'. and 2| and alongittudinal stiffening rib 22, all permanently secured together bywelding or'brazing in the relative in Figs. 8 and 9. The propeller bladeB is also provided with the usual hollow circular hub portion 24 bywhich it is attached to the driving shaft of a suitable engine. i gs Theblank 2| from which the casing portion It is the general object of myinvention to be' joined together is formed-is shown in cross section inFig. 3 and comprises two. flat and relatively thin side portions 2| and2'8 and a relatively heavy upset rib 21 located opposite a depressedportion or groove 28.

It will be understood that the portions 25 and 5 26 vary in width indifferent parts of the blank, so as to provide the required stock toform a blade of the varying cross section indicated in Figs. 1,

, 8 and 9. v I

The blank 2 I shown in Figs. 2 and 4 is similarly provided with flatportions and 36 separated by a relatively heavy upset rib 21 locatedopposite a depressed portion or groove 38.

After the blanks are formed as described by forging or press operations,the blanks are pressed and folded as indicated by the arrows in Figs. 3and 4 to the U-shaped sections shown in Figs. 5 and 6. This operation ispreferably performed by dies in such manner that the surfaces will bebrought to the exact contours required in the finished blade.

The longitudinal strengthening rib 22 is then placed between the edgesof the portions 20 and 2| of the blade and the parts are permanentlysecured together by welding or brazing operations.

In order that all parts may be firmly held from displacement during saidwelding or brazing operation, the edges of the rib 22 are preferablyrecessed as indicated at 40 in Fig. 10 to receive the edges of theforged casing portions 2|) and 2|, which edges have'previously beenmachined to the exact required outlines.

During the pressing and folding operation the hub portions 42 and 42(Fig. 2) of the blanks may be bent to semicircular form and these partsmay to form the complete hub2l when the other parts of the blade arewelded or brazed.

Having thus described my improved'propeller bladeand my improved methodof making the same, it will be seen that I have produced a hollow steelpropeller blade comprising two forged casing portions strong yreenforced at the edges of the blade, and a single additionallongitudinal stiffening member to which the forged portions arepermanently welded or brazed.

, Such a propeller blade has the desired light weight associated withthe necessary high tensile strength, and is adapted to resist the severestresses-to which it is subject in operation.

The blade may be twisted to provide the necessaryhelical pitch at anyconvenient point inthe operations d Preferably the blade is twistedafter the parts are assembled as shown in Figs. 8 and 9 but before thewelding operation, ll

Having thus described my invention and the advantages thereof, I do notwish to be limited to the details herein disclosed, otherwise than asset forth in the claim but what I claim is:

The method of making a hollow metal propeller blade having curved frontand rear outer edges and which tapers gradually in width from anintermediate point toward the outer end and abruptly in width from saidintermediate point toward the inner end; which method comprises forminga pair of substantially fiat forged blanks each having one straight edgeand one curved edge and each being widest intermediate its ends andtapering toward the ends; forming in each blank-an integral longitudinalrib of substantially greater thickness than the flat portion of theblank and near the center 01 the blank which rib is in partlongitudinally curved and follows a line approximately midway betweenthe variably spaced edges of said blank throughout the major portion ofthe length of said blank; bending each blank about its longitudinal ribthereby forming therefrom complementary casing portions of substantiallyU-shaped cross section and tapering toward each end; assembling saidU-shaped casing portions with the rib portions outermost and theinneredges engaging a longitudinal metal stiflening member; and permanentlysecuring the easing sections and said stiffening member by welding theparts together along the lines of 'junct e, thereby forming a completepropeller blade, wherein the curved oflset ribs constitute integralreinforced curved edges for the blade.

JOHN H. NELSON.

